Make sure BDSM is promoted in sex ed, so more people already have these items when the outbreak happens. Reduces costs and increases society's sexiness factor.

More seriously, for that use I'd recommand handcuffs with a release button. Zombies wouldn't be able to operate it, but if the victim ends up not dying, they'd be able to rapidly free themselves. (Because keys would CERTAINLY end up at the bottom of your bag by the time you need that, it's obligatory. Even if you weld them to the cuffs, they'll fall.) This way they would be less tempted to wait for the very last minute to put it on "just in case".

Ok, I had advocated before that everyone in the world should have to wear full face helmets to prevent bites from turned people, but I will admit this would be a lot kinkier and entertaining on several levels.